Hydraulic control device for highpressure liquid-fuel-supply pumps of pressure-atomizing oil burners



Dec. 15, 1953 J, LOGAN ET AL 2,662,542

HYDRAULIC CONTROL DEVICE FOR HIGH-PRESSURE LIQUID-FUEL-SUPPLY PUMPS OFPRESSURE-ATOMIZING OIL BURNERS Filed Dec. 22, 1951 INVENTORJ- JossrnAloamv Aw 1 2 0 1 2 65000517. Foe/45o Jzcolvos \SZEco/ww BY .7,

ATTORNEYS Patented Dec. 15, 1953 when HYDR ULHC CONTROL DEVICE FOR HIGH--FUEL-SUPPLY PUMPS PRE S SURE LIQUID OF PRESSURE-AT OMIZING OIL BURNERSJoseph A. Logan, Hadley, son, Agawam, Mass, Barker Manufacturing field,Mass, a corporati and George D. Robinassignors to Gilbert & Company,West Springon of Massachusetts Application December 22, 1951, Serial No.262,954

6 Claims.

This invention relates to an improved hyd'raulically-operable controldevice for connection to the high-pressure liquid-fuel-supply pump of apressure-atomizing type of oil burner for modifying the oil pressureconditions at the start and at the end of each cycle of burneroperation.

The invention has for its object the provision of a control device ofcomparatively simple and inexpensive construction that can be sold todealers or distributors of oil burners and attached, without requiringspecial skill, to oil burners, regardless of make or construction, solong as they utilize a high-pressure fuel-supply pum and that willmaterially improve the operation of the burner and enable highereniciency of combustion to be obtained.

More particularly, the invention is adapted to be applied to an oilburner of the pressure-atomizing type, which is adapted forhouse-heating service, and which operates intermittently under automaticcontrol and started and stopped many times during each day of theheating season. These burners customarily have positively-actingfue1-supply pumps, which have a pumping rate far in excess of that atwhich the fuel is consumed, the major part of the pumped 'fuel beingby-passed. These pumps, if started simultaneously with the air-supplyfan, build up the required high-atomizing pressure, say for eX- ample100 p. s. i., very rapidly, almost instantaneously, and long before thefan, which is nonpositive in action, can get the air moving past thefuel nozzle at the rate necessary to secure good combustion.Consequently, the fuel-air mixture will be over rich during the startinginterval of operation of the burner, resulting in initially smokyoperation, unless the burner is adjusted to admit excess air, and insuch case the efficiency of combustion, during normal running intervalsof operation, will be decreased. The device of this invention is adaptedto delay the building up of the rated fuel pressure for a short time,say for example, a few seconds, and long enough to enable the fan toreach full speed and get the air for combustion moving past the fuelnozzle at the proper rate for good and cilicient combustion. It is alsoimportant to modify the oil pressure at the end of each cycle of burneroperation with the object of cutting off the oil flow to the burnernozzle as soon as possible after the power to the burner motor is cutoff, and the control device of this invention enables the combustionconditions atthe end of each Lburner cycle to be materially improved bycausing a quicker closure of the cut-off valve in the oil supply systemof the burner than would otherwise be possible.

The invention will be disclosed with reference to an illustrativeexample of it in the accompanying drawings, in which,

Fig. 1 is a full-size sectional-elevational view of a control deviceembodyingthe invention, the parts being shown in the positions whichthey occupy when the fuel-supply pump is stopped; this view also shows,diagrammatically and on a small scale, a fuel-supply system for an oilburner of the class described;

Fig. 2 is a similar view of the control device only, the parts thereofbeing shown in the positions, which they occupy at the end of the timedelay interval on starting the pump;

Fig. 3 is a graph showing how the building up of oil pressure in theconduit supplyin the atomizing nozzle of the burner is delayed at thestart of each cycle of operation of the burner; and

Fig. 4 is a graph showing how the oil pressure in the supply conduit forthe atomizing nozzle is quickly cut off following the cutting on ofpower to the motor, which drives the oil supply Referring to thesedrawings; the control device includes a chamber, such as a cylinder l,formed within a casing, such as a tubular barrel 2, having heads 3 and4, suitably fixed, one in each of the ends of the barrel. As shown, head3 has a drive fit in one end of barrel 2 and head 4 has aneXteriorly-threaded annular portion 5, which is screwed into theinteriorly-threaded end of the barrel 2. A gasket 6 seals the jointbetween the head 4 and the barrel. The control device also includes amovable wall in the chamber I, such as a piston'l. A spring 8, actingbetween one face of the piston and the head l, and partially telescopedwithin the annular portion 5, tends to move the piston into engagementwith head 3 and hold it-in the position shown in Fig. 1. As shown,piston i has a circumferential groove, containing an O-ring which mayfor example be of synthetic rubber and which prevents leakage of liquidpast the piston. Inlet and outlet ports it and H, respectively, areprovided for cylinder I and, as shown, these ports are respectivelyformed in the heads 3 and 4. The piston 7 has a passage 22 therethroughand at least a portion of this passage is of very small diameter, in thepresent example .024". The piston is adapted to be moved by the pressureof oil which enters inlet It, away from head 3 and to the right until itabuts the end face of the annular portion 5 as a stop. The passage 12 isso located as to communicate at such time with the space 13 within theannular portion 5. This space 13 communicates with one end of an axialpassage M in head 4. The other end of passage I4 opens into the innerend of a coaxial passage IS, the outer end of which is closed by a plug16, screw outer end of the passage l5, and sealed by a gasket H. Theintersection of the passages 14 and i5 affords a seat for a ball valvel8. which is held to its seat by a spring l9 acting between the ball andthe closure plug IS. A radial passage in head 4 connects the passage l5with the outlet port II.

The control device described is especially adapted for use in connectionwith the high-- pressure positively-acting, fuel-supply pumps commonlyused in oil burners of the mechanical or pressure-atomizing type such asare adapted for house heating service and are started and stopped manytimes each day under automatic thermostat control. One purpose is todelay the emission of oil from the atomizing nozzle until the motor,which drives the pump and also a non-positively-acting, air-supply fan,has acquired high speed, and preferably full speed, in order to securethe proper rate of air flow to result in good combustion. Anotherpurpose is to secure a quick cutting off of oil flow to the nozzle afterthe pump motor is deenergized.

Fig. 1 shows diagrammatically and on a small scale, the fuel-supplymeans for a pressure atomizing oil burner of the class described. A pump25, adapted for connection to a fuel-supply by suction pipe 23, forcesoil through a conduit 21 to a casing 28, containing a bypass valve 29,and from such casing through a conduit 30 to a casing 3!, containing acut-off valve 32. The pump, in the present example, is designed to pumpoil at the rate of 18 gallons per hour. The outlet of casing 3|, whichis controlled by valve 32, is connected by a conduit 33 to themechanical or pressure-atomizing nozzle 34 of the oil burner. Thenozzle, in the present example, is rated to deliver oil at the rate of 2gallons per hour when supplied with oil at 100 p. s. i. The outlet ofcasing 28, which is con trolled by valve 29, is connected by a bypassconduit 35 to the suction side of pump 25, as to pipe 26. The pump has ascrew plug 35, which may be loosened in order to rid the system of air,whenever necessary, as for example, when initially installing the burneror whenever the pump. after having stopped because of exhaustion of theoil supply, is subsequently started.

The cut-off valve 32 is held closed by a Sprin 31 until the pressure ofpumped oil reaches a predetermined minimum value, say for example about90 p. s. i. The bY-pass valve 29 is held closed by a spring 38 until thepressure of the pumped oil reaches a predetermined maximum value, sayfor example, 100 p. s. i., which is the normal operating pressure. Theinlet of the control device is adapted to be connected to the pressureside of the oil pump between its outlet and the by-pass and cut-offvalves and, as indicated by the dot-dash line 39, to conduit 21. Theoutlet H is adapted for connection to the suction side of the oil pump,and, as indicated by the dot-dash line 40 to pipe. 26.

In an oil-supply system of the type described. the pump 25 must bevented initially and each time after the fuel-supply has becomeexhausted.

threaded into the K in order to rid the system of air. The only outletsfor the pump are usually closed by valves, such as 29 and 32 which openat relatively high pressures, greater than any that the pump can producewhen pumping air alone. For example, in the present case, the greatestpressure which pump 25 can produce, when pumping air is 20 p. s. i.Hence, the valve 32 will not open and allow air to escape from nozzle34. Therefore, the plug 36 on the pump is provided and this plug, whenloosened, will afford an outlet for the pump air to escape. As soon asoil appears, the plug 38 is screwed in tightly and the system will thenoperate in the normal manner.

The control device provides by the passage l2 through its piston aby-pass between the inlet and outlet of the pump that is continuouslyopen during normal operation. This bypass has to be closed before aircan be eliminated from the fuel-supply system of the burner. The checkvalve I8 automatically closes this by-pass to enable elimination of airto be effected, when required, and yet enables the by-pass to be openduring normal operation of the burner to accomplish its purpose. Thespring i9 is designed so that the check valve l8 will open at 25 p.s. 1. Thus, this valve l8 cannot open, when the pump is pumping airalone. The same result might be effected by manual closure of a handvalve, such as 4!, in the pipe 40, whereby the valve It might beeliminated but it is desirable and preferred because it takes care ofthe condition automatically without requiring any attention on the partof the operator.

The spring 8 is designed to have sufficient force to return the pistonfrom the Fig. 2 to the Fig. 1 position, when the oil pump stops. Thisspring must have sufficient force to overcome the friction of the O-ring9 sliding on the wall of cylinder i and also to force oil from the lefthand to the right hand side of the piston through the restricted portionof the passage 12 in the piston, and the spring 8 must yield before thecheck valve 18 opens. In the present example, this spring 0, when fullystressed, exerts a force of 23 p. s. i. on the piston.

Normally, the parts of the control device will occupy the positionsshown in Fig. 1, when the burner is not in operation. When the pump isstarted, it will very quickly build up a pressure of 25 p. s. i., andopen check valve 18 and thus open the by-pass around the pump. Thepiston I will then move slowly to the right under pressure of the pumpedliquid. Some oil may pass through the passage l2 in the piston but,initially, the rate of flow therethrough is only verty small compared tothat at which oil is forced out of the pump and into the cylinder I.After the piston has engaged its stop, more and more oil will flowthrough the passage [2 until at the full operating pressure a rate ofabout 4.5 gallons per hours is established. The passage I2 is not animportant factor in delaying the building up of the atomizing pressure.The major factor is the expansible chamber afforded by the cylinder andpiston 1. This cylinder has a relatively large volume which has to befilled before the pump can build up the high pressure necessary to openthe cut-off and by-pass valves 32 and 29, respectively, and it is thedisplacement of the piston in the cylinder that is relied on to producethe desired time delay. The signiflcant factors in producing the timedelay are the cross sectional area of. cylinder I and the length ofstroke of its piston.

The pressure will slowly rise from 25 p. s. i. as the piston moves tothe right but not until the piston is arrested by its stop, does thesharp increase occur that is necessary to open the cut-off valve a2 andshortly after the by-pass valve The result is indicated in 3 by thegraph M, which shows pressure in the supply conduit plotted. againsttime in seconds after the starting of the pump. The cut-off valve 32remains closed for 2.4 seconds after the pump 25 is started and nopressure exists in the supply conduit at until this valve does open.When cut-oil valve 32 opens, at around 90 p. s. i., there is a veryrapid rise in pressure to the full atomizing pressure of 100 p. s. i.,when the by-pass valve 29 opens to maintain the pressure of oil suppliedto conduit 33 constant. It will thus be seen that the corn trol deviceenables a delay in the opening of the cut-off valve 32 and thus thesupply of oil to the atomizing nozzle This delay is adequate to enablethe burner fan to reach full speed and move air past the nozzle at asufiicient rate to effect eihcient and smokeless combustion.

For the control device to be thoroughly satisfactory, it must do morethan merely delay the supply of oil to the atomizing nozzle ti l. Itmust also modify the oil pressure at the end of the cycle of burneroperation. This is the function of the by-pass passage I2 in the piston.There needs to be available at the insta t, when the power to pump 25 isout 01?, a bypass that will cause a quick drop in pressure. Without sucha by-pass, the pressure will diminish only as the speed of the pumpdiminishes and this would require considerable time because the pump isoversize. At the same time, this by-pass must be restricted because itis always open during normal intervals of operation of the burner andcauses a great deal of oil to be lay-passed. In the present example, oilis by-passed at the rate of 4.5 gallons per hour. Thus, 25% of thepumped oil is by-passed through the passage i2. If the diameter of therestricted portion of this passage were doubled, its area would bequadrupled and the device and burner would be inoperative because allthe pumped oil would be by-passed through passage i2 and the pump couldnever build up pressure enough to open the cutoii valve 32. The area ofthis passage is therefore critical. The effect of the by-pass around thepiston is shown in the graph 43 of Fig. 4, which shows oil pressure inthe nozzle-supply-conduit plotted against time in seconds after thepower to the pump motor has been cut-off. There is a gradual drop inpressure until the cut-off valve 32 closes, which occurs in .7 second,followed by a rapid decrease in pressure to zero. With a slight increasein diameter of the restricted portion of passage I 2 to .028", the timenecessary to cause closure of the cut-ofi valve will be reduced to .3second and the time delay will be increased to 3 seconds but the amountof oil by-passed through passage it will be increased to 3 gallons perhour, which is considered too much to be safe to rely on in commercialpractice. The practical limit on the size of the restricted portion ofpassage iii that which would by pass no more than a third of the ratedcapacity of the pump.

The invention thus provides a control device, which is readily installedin an oil burner to control pressure conditions in the oil supply to theatomizing nozzle, so as to be effective, on starting of the pump, todelay the building up of at pressure long enough for the fan toestablish the full rate of air flow to secure good combustion and so asto be efiective, on stopping of the pump, to quickly cut-off the supplyof oil to the nozzle and avoid the pufi of smoke that would otherwiseoccur due to the rapidly diminishing rate of air flow.

What is claimed is:

l. A hydraulically-operable ccntrol device for the high-pressurefuel-supply pump of a sure-atomizing oil burner, comprising, a tuhularbarrel affording within it a cylinder, heads closing opposite ends ofthe cylinder and provided one with an inlet and the other with an outlettherethrough, the head provided with the outlet passage having anexteriorly threaded annular part screw threaded into one end of saidbarrel and the entrance to the outlet passage opening into the spacewithin the annular portion, a piston slidable in said cylinder, a springacting between the piston and the last-named head and in part telescopedwithin said annular part for movin the piston against the other head andadapted to yield under pressure of oil pumped into said inlet to allowthe piston to move toward and into engagement with the end face of saidannular portion, said piston having a passage of restricted areatherethrough for interconnecting the inlet end of the cylinder to thespace within said annular portion and thus to the outlet when the pistonengages said end face.

2. The combination as claimed in claim 1, in which a spring closed checkvalve is mounted in the outlet passage and opens at a pressure slightlygreater than that exerted by the first-named spring on the piston whenthe latter is engaged with said end face as a stop.

3. A hydraulically-operable control device, adapted to be connected inby-pass relation with a fuel-supply pump having a predetermined maximumpumping rate and adapted to supply oil at a predetermined maximumpressure to a pressure-atomizing oil burner, comprising, a cas ingaffording a chamber having a single inlet near one end and a singleoutlet near the other end and being otherwise closed, said inlet andoutlet being respectively adapted for connection to the pressure andsuction sides of a pump, a wall partitioning said chamber and interposedbetween said inlet and said outlet and having two opposite sides oneconfronting the inlet end and the other confronting the outlet end ofsaid chamber, said wall being mounted for movement between two extremepositions one near said inlet end and the other near said outlet end, acontinuously-open conduit afiording a by-pass for said wallinterconnecting the spaces in said chamber on opposite sides of saidwall at all positions of the latter, throughout its range of movement,said conduit having a portion of restricted cross sectional area ascompared to the cross-sectional area of said inlet and outlet, and aspring tending to move said wall from its secend-named extreme positionto its first-named extreme position, said spring being yieldable at apressure much lower than said predetermined maximum pressure and saidwall adapted to be moved from the second-named to the first-namedextreme position by pressure of liquid supplied to said inlet.

4,. The combination, as claimed in claim 3, in which said maximumpressure is several times said second-named pressure.

5. The combination, as claimed in claim 3, having a valve controllingsaid outlet and a spring for holding said valve closed and yielding at apressure about equal to said second-named predetermined pressure.

6. The combination, as claimed in claim 3, in which the restrictedportion of the by-pass conduit has a cross sectional area such as topass oil under said maximum pressure at a rate no greater than one thirdof said maximum rate.

JOSEPH A. LOGAN. GEORGE D. ROBINSON.

8 References Cited in the file of this patent UNITED STATES PATENTSNumber Name Date Nightingale et a1. Aug. 30, 1932 Murphy Mar. 3, 1936Murphy Sept. 30, 1941 Logan Feb. 15, 1949

